Piezoelectric actuator, and timepiece and portable equipment having the same

Abstract

A diaphragm 10 is fixed to a base plate 102 by a screw 13 . A lever 20 has a spring member 23 , a rotor-fixing member 25 , and an insertion hole 22 formed therein. By passing a shaft 21 through the insertion hole 22 , the lever 20 is turnably supported so as to turn about its own axis. In a state in which the spring member 23 abuts against an eccentric pressure-adjusting cam 26 , a pressing force for urging the diaphragm 10 via the rotor 100 is adjusted by turning the pressure-adjusting cam 26 so as to change an elastic force of the spring member 23.

1. A piezoelectric actuator, comprising:
 a base;  
 a diaphragm which comprises at least one plate-like piezoelectric element and a plate-like backing material affixed thereto and which is adapted to move in the plane of the diaphragm in response to a drive signal applied thereto, the backing material comprising 
 a fixing member that is fixed to the base so as to eliminate rotational movement of the diaphragm and to restrict movement of the diaphragm to the plane of the diaphragm, and  
 an abutment member disposed on the diaphragm; and  
 
 a pressing mechanism configured to apply a pressing force so as to engage the abutment member with an object to be driven.  
 
   
   
     2. The piezoelectric actuator according to  claim 1 , wherein the fixing member maintains the at least one piezoelectric element in a position spaced apart from the base. 
   
   
     3. The piezoelectric actuator according to  claim 1 , further comprising an adjusting mechanism for adjusting the pressing force applied by the pressing mechanism. 
   
   
     4. The piezoelectric actuator according to  claim 1 , wherein the pressing mechanism comprises a spring. 
   
   
     5. The piezoelectric actuator according to  claim 4 , wherein the spring has a curved shape. 
   
   
     6. The piezoelectric actuator according to  claim 1 , wherein the fixing member is fixed to the base by a screw. 
   
   
     7. The piezoelectric actuator according to  claim 1 , wherein
 the at least one plate-like piezoelectric element comprises first and second piezoelectric elements respectively stacked on front and rear surfaces of the backing material, each of the first and second piezoelectric elements comprising a plurality of electrode plates,  
 the fixing member is formed as a part of the backing material and extends out from the piezoelectric elements, the fixing member comprising a lead board fixed thereto, the lead board including contact terminals for electrically connecting the lead board to a drive circuit configured to generate the drive signal and to drive the first and second piezoelectric elements, and  
 each of the plurality of electrode plates of the first and second piezoelectric elements has at least one contact spot that is connected to a contact terminal on the lead board by a bonding wire, each contact terminal and contact spot and portion of the bonding wire connected thereto being covered by a potting layer.  
 
   
   
     8. The piezoelectric actuator according to  claim 7 , wherein two of the electrode plates are connected to each other by a bonding wire extending around a side edge of the diaphragm. 
   
   
     9. The piezoelectric actuator according to  claim 7 , wherein each of the contact spots provides a node point in the corresponding electrode plate when the diaphragm vibrates. 
   
   
     10. The piezoelectric actuator according to  claim 7 , further comprising:
 a circuit board equipped with the drive circuit, the circuit board including contact terminals for electrical connection to the drive circuit; and  
 a pressing-force applying mechanism configured to apply a pressing force between the lead board and the circuit board to maintain electrical contact between corresponding contact terminals on the boards.  
 
   
   
     11. The piezoelectric actuator according to  claim 10 , wherein the pressing-force applying mechanism also fixes the fixing member to the base. 
   
   
     12. The piezoelectric actuator according to  claim 11 , wherein the pressing-force applying mechanism also has a screw-fastening function. 
   
   
     13. The piezoelectric actuator according to  claim 1 , wherein
 the at least one plate-like piezoelectric element comprises first and second piezoelectric elements respectively stacked on front and rear surfaces of the backing material, each of the first and second piezoelectric elements comprising a plurality of electrode plates, and  
 the plurality of electrode plates of the first and second piezoelectric elements are electrically connected to a flexible printed circuit board extending to the fixing member which is formed as a part of the backing material and which extends out from the piezoelectric elements.  
 
   
   
     14. The piezoelectric actuator according to  claim 13 , wherein two of the electrode plates are connected to each other by the flexible printed circuit board extending around a side edge of the diaphragm. 
   
   
     15. The piezoelectric actuator according to  claim 13 , wherein each spot of the electrode plates which is connected to the flexible printed circuit board provides a node point in the corresponding electrode plate when the diaphragm vibrates. 
   
   
     16. The piezoelectric actuator according to  claim 13 , further comprising:
 a circuit board equipped with a drive circuit and including contact terminals electrically connected to the drive circuit; and  
 a pressing-force applying mechanism configured to apply a pressing force between a portion of the flexible printed circuit board extending to the fixing member and the circuit board to maintain electrical contact between corresponding contact terminals on the boards.  
 
   
   
     17. The piezoelectric actuator according to  claim 16 , wherein the pressing-force applying mechanism also fixes the fixing member to the base. 
   
   
     18. The piezoelectric actuator according to  claim 17 , wherein the pressing-force applying mechanism also has a screw-fastening function. 
   
   
     19. A piezoelectric actuator, comprising:
 a base;  
 a diaphragm which comprises at least one plate-like piezoelectric element and a plate-like backing material affixed thereto and which is adapted to move in the plane of the diaphragm in response to a drive signal applied thereto, the backing material comprising 
 a fixing member that is fixed to the base so as to eliminate rotational movement of the diaphragm and to restrict movement of the diaphragm to the plane of the diaphragm, and  
 an abutment member disposed on the diaphragm;  
 
 an object to be driven in response to movement of the diaphragm via the abutment member which is in contact with the object to be driven; and  
 a pressing mechanism configured to apply a pressing force on the abutment member from the object to be driven.  
 
   
   
     20. The piezoelectric actuator according to  claim 19 , wherein
 the object to be driven comprises a rotor adapted to rotate in response to a drive force transmitted by the abutment member resulting from movement of the diaphragm, and  
 the pressing mechanism comprises a lever having a rotor-fixing member at one end portion thereof adapted to rotatably hold the rotor and a spring at another end portion thereof for producing an elastic force as the pressing force.  
 
   
   
     21. The piezoelectric actuator according to  claim 19 , further comprising an adjusting mechanism configured to adjust the elastic force applied by the pressing mechanism. 
   
   
     22. The piezoelectric actuator according to  claim 21 , wherein
 the object to be driven comprises a rotor adapted to rotate in response to a drive force transmitted by the abutment member resulting from movement of the diaphragm,  
 the pressing mechanism comprises a spring adapted to urge the rotor against the abutment member, and  
 the adjusting mechanism comprises an eccentric cam which is rotatably supported by the base so as to rotate about its own axis and which adjusts the pressing force that urges the rotor against the abutment member by forcibly pressing one end thereof against the spring.  
 
   
   
     23. The piezoelectric actuator according to  claim 19 , wherein
 the object to be driven comprises a rotor adapted to rotate in response to a drive force transmitted by the abutment member resulting from movement of the diaphragm,  
 the pressing mechanism comprises a lever that comprises a rotor-fixing member at one end portion thereof adapted to rotatably hold the rotor and a spring at another end portion thereof to produce an elastic force, and  
 the adjusting mechanism comprises an eccentric cam which is rotatably supported by the base so as to rotate about its own axis and which adjusts the pressing force that urges the rotor against the abutment member by forcibly pressing one end thereof against the spring.  
 
   
   
     24. A timepiece, comprising:
 a piezoelectric actuator comprising: 
 a base,  
 a diaphragm which comprises at least one plate-like piezoelectric element and a plate-like backing material affixed thereto and which is adapted to move in the plane of the diaphragm in response to a drive signal applied thereto, the backing material comprising 
 a fixing member that is fixed to the base so as to eliminate rotational movement of the diaphragm and to restrict movement of the diaphragm to the plane of the diaphragm, and  
 an abutment member disposed on the diaphragm, and  
 
 a pressing mechanism configured to apply a pressing force so as to engage the abutment member with an object to be driven;  
 
 a drive circuit for supplying the drive signal to the at least one piezoelectric element;  
 a power source for supplying power to the drive circuit; and  
 means for indicating time-information driven by the piezoelectric actuator.  
 
   
   
     25. The timepiece according to  claim 24 , wherein the at least one plate-like piezoelectric element comprises a plurality of electrode plates, all of which are electrically insulated from a reference potential portion of the time piece. 
   
   
     26. The timepiece according to  claim 25 , wherein the base comprises a non-conductive material. 
   
   
     27. The timepiece according to  claim 25 , further comprising an insulating plate sandwiched between the base and the fixing member. 
   
   
     28. A portable apparatus, comprising:
 a piezoelectric actuator comprising: 
 a base,  
 a diaphragm which comprises at least one plate-like piezoelectric element and a plate-like backing material affixed thereto and which is adapted to move in the plane of the diaphragm in response to a drive signal applied thereto, the backing material comprising 
 a fixing member that is fixed to the base so as to eliminate rotational movement of the diaphragm and to restrict movement of the diaphragm to the plane of the diaphragm, and  
 an abutment member disposed on the diaphragm, and  
 
 a pressing mechanism configured to apply a pressing force so as to engage the abutment member with an object to be driven;  
 
 a drive circuit for supplying the drive signal to the at least one piezoelectric element;  
 a power source for supplying power to the drive circuit; and  
 an object to be driven by the piezoelectric actuator.  
 
   
   
     29. The portable apparatus according to  claim 28 , wherein the at least one plate-like piezoelectric element comprises a plurality of electrode plates, all of which are electrically insulated from a reference potential part of the portable apparatus. 
   
   
     30. The portable apparatus according to  claim 29 , wherein the base comprises a non-conductive material. 
   
   
     31. The portable apparatus according to  claim 29 , further comprising an insulating plate sandwiched between the base and the fixing member.